U.S. patent number 5,827,289 [Application Number 08/659,678] was granted by the patent office on 1998-10-27 for inflatable device for use in surgical protocols relating to treatment of fractured or diseased bones.
Invention is credited to Mark A. Reiley, Arie Scholten, Karen D. Talmadge.
United States Patent |
5,827,289 |
Reiley , et al. |
October 27, 1998 |
Inflatable device for use in surgical protocols relating to
treatment of fractured or diseased bones
Abstract
A balloon for use in compressing cancellous bone and marrow
(also known as medullary bone or trabecular bone) against the inner
cortex of bones whether the bones are fractured or not. The balloon
comprises an inflatable, non-expandable balloon body for insertion
into said bone. The body has a shape and size to compress at least
a portion of the cancellous bone to form a cavity in the cancellous
bone and to restore the original position of the outer cortical
bone, if fractured or collapsed. The balloon is prevented from
applying excessive pressure to the outer cortical bone. The wall or
walls of the balloon are such that proper inflation the balloon
body is achieved to provide for optimum compression of all the bone
marrow. The balloon is able to be folded so that it can be inserted
quickly into a bone. The balloon can be made to have a suction
catheter. It can also be coated with therapeutic substances. The
main purpose of the balloon is the forming or enlarging of a cavity
or passage in a bone, especially in, but not limited to, vertebral
bodies. Another important purpose is to deliver therapeutic
substances to bone in an improved way.
Inventors: |
Reiley; Mark A. (Piedmont,
CA), Scholten; Arie (Freemont, CA), Talmadge; Karen
D. (Palo Alto, CA) |
Family
ID: |
27761623 |
Appl.
No.: |
08/659,678 |
Filed: |
June 5, 1996 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
485394 |
Jun 7, 1995 |
|
|
|
|
188224 |
Jan 26, 1994 |
|
|
|
|
Current U.S.
Class: |
606/86R; 606/60;
606/192; 606/191 |
Current CPC
Class: |
A61F
2/28 (20130101); A61B 17/8855 (20130101); A61M
25/10 (20130101); A61B 17/7258 (20130101); A61M
25/1002 (20130101); A61F 2/4601 (20130101); A61B
90/94 (20160201); A61F 2/441 (20130101); A61B
10/025 (20130101); A61F 2/4611 (20130101); A61F
2220/005 (20130101); A61F 2002/30225 (20130101); A61F
2002/4685 (20130101); A61M 2025/1072 (20130101); A61F
2002/30125 (20130101); A61F 2002/302 (20130101); A61F
2002/30599 (20130101); A61F 2002/4062 (20130101); A61F
2002/4217 (20130101); A61F 2002/30285 (20130101); A61B
2017/00544 (20130101); A61F 2230/0065 (20130101); A61F
2002/30313 (20130101); A61M 2025/105 (20130101); A61B
17/742 (20130101); A61F 2002/30245 (20130101); A61F
2002/30581 (20130101); A61F 2002/30686 (20130101); A61F
2002/30909 (20130101); A61F 2230/0076 (20130101); A61F
2002/30253 (20130101); A61F 2310/00293 (20130101); A61B
50/33 (20160201); A61F 2002/30586 (20130101); A61B
2050/3015 (20160201); A61F 2002/30113 (20130101); A61B
17/025 (20130101); A61F 2220/0075 (20130101); A61F
2002/2835 (20130101); A61F 2002/30228 (20130101); A61M
2210/02 (20130101); A61F 2002/30242 (20130101); A61B
2017/00557 (20130101); A61F 2002/30677 (20130101); A61F
2230/0013 (20130101); A61F 2002/2825 (20130101); A61F
2002/2832 (20130101); A61F 2310/0097 (20130101); A61B
2017/00539 (20130101); A61F 2002/30131 (20130101); A61F
2310/00353 (20130101); A61B 17/00234 (20130101); A61B
17/744 (20130101); A61F 2/389 (20130101); A61F
2002/2817 (20130101); A61F 2002/30308 (20130101); A61F
2230/0063 (20130101); A61M 25/1011 (20130101); A61F
2002/2853 (20130101); A61F 2002/30133 (20130101); A61F
2230/0071 (20130101); A61F 2002/30448 (20130101); A61F
2002/30115 (20130101); A61F 2002/3611 (20130101); A61B
2017/0256 (20130101); A61F 2002/30288 (20130101); A61F
2002/4635 (20130101); A61B 2010/0258 (20130101); A61F
2002/2892 (20130101); A61F 2002/30462 (20130101); A61F
2002/3625 (20130101); A61F 2250/0063 (20130101); A61F
2002/2828 (20130101); A61B 2050/0065 (20160201); A61F
2/3601 (20130101); A61F 2/44 (20130101); A61F
2002/2871 (20130101); A61M 2210/1003 (20130101); A61B
90/39 (20160201); A61F 2230/0008 (20130101); A61F
2230/0006 (20130101); A61F 2230/0015 (20130101); A61F
2/2846 (20130101); A61F 2230/0069 (20130101) |
Current International
Class: |
A61B
17/72 (20060101); A61B 17/68 (20060101); A61B
17/88 (20060101); A61F 2/46 (20060101); A61M
25/10 (20060101); A61F 2/28 (20060101); A61F
2/30 (20060101); A61F 2/00 (20060101); A61F
2/36 (20060101); A61F 2/38 (20060101); A61F
2/40 (20060101); A61F 2/44 (20060101); A61B
17/02 (20060101); A61B 17/00 (20060101); A61B
017/56 () |
Field of
Search: |
;606/60,62,63,86,87,89,191,192 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
439636 |
|
May 1912 |
|
FR |
|
3736604 |
|
May 1989 |
|
DE |
|
9001858 |
|
Mar 1992 |
|
NL |
|
906530 |
|
Feb 1982 |
|
RU |
|
1148610 |
|
Apr 1985 |
|
RU |
|
512 456 |
|
Sep 1939 |
|
GB |
|
Other References
Riggs et al. New England Journal of Medicine (1986) 1676-1686.
Medical Progress, Involutional Osteoporosis. .
Cohen et al. The Orthopedic Clinics of North America (1990)
21:143-152. Fractures of the Osteoporotic Spine, Pathologic
Fractures in Betabolic Bone Disease. .
Silverman Bone (1992) 13:S27-S31. The Clinical Consequences of
Vertebral Compression Fracture. .
Melton et al. Journal of Bone and Mineral Research (1992)
7:1005-1010. Perspective: How Many Women Have Osteoporosis. .
K. Harrington The Journal of Bone and Jount Surgery (1972)
54A:1665-1676. The Use of Methylmethacrylate as an Adjunct in the
Internal Fixation of Malignant Neoplastic Fractures. .
Instructions entitled "Exeter Pressurizer system", by Howmedica
Inc., Orthopaedics Division, 1979, 2 pages. .
B. Lawrence Riggs, M.D. et al. "Medical Progress, Involutional
Osteoporosis", The New England Journal of Medicine, Jun. 26, 1986,
pp. 1676-1686. .
Lawrence D. Cohen, M.D., "Fractures of the Osteoporotic Spine",
Pathologic Fractures in Betabolic Bone Disease, the Orthopedic
Clinics of North America, vol. 21:1, Jan. 1990, pp. 143-152. .
S. L. Silverman, "The Clinical Consequences of Vetebral Compression
Fracture", Bone, 13, S27-S31 (1992)..
|
Primary Examiner: Buiz; Michael Powell
Assistant Examiner: Shai; Daphna
Attorney, Agent or Firm: Ryan, Maki, Mann &
Hohenfeldt
Parent Case Text
This application is a continuation-in-part of U.S. patent
application Ser. No. 08/485,394, filed Jun. 7, 1995, now abandoned,
which is a continuation-in-part of U.S. patent application Ser. No.
08/188,224, filed Jan. 26, 1994 entitled, "Improved Inflatable
Device For Use In Surgical Protocol Relating To Fixation Of Bone,
now abandoned."
Claims
We claim:
1. A device for insertion into a hip bone having an interior volume
occupied, at least in part, by cancellous bone, the device
comprising
a body having an axis and capable of expansion about the axis from
a collapsed geometry, adapted for insertion into the interior
volume, and an expanded geometry, adapted for compacting cancellous
bone in the interior volume,
a first essentially inelastic band extending along the axis,
and
a second essentially inelastic band extending along the axis spaced
from the first essentially inelastic band, the first essentially
inelastic band and the second essentially inelastic band having
different axial lengths to restrain expansion such that the body
bend along the axis during expansion.
2. A device according to claim 1
wherein the first and second essentially inelastic bands bias the
body, when in the expanded geometry, toward a curved shape.
3. A device according to claim 1
wherein the first and second essentially inelastic bands are
generally diametrically spaced along the axis.
4. A device according to claim 1
and further including at least one ring encircling the body about
the axis and coupled to the first and second essentially inelastic
bands.
5. A device according to claim 4
wherein the at least one ring comprises an essentially inelastic
material.
6. A device according to claim 1
wherein the body comprises an essentially inelastic material.
7. A device according to claim 1
wherein the body comprises an essentially semi-elastic
material.
8. A device according to claim 1
wherein the body comprises an essentially elastic material.
9. A device according to claim 1
and further including a catheter tube having a distal end, and
wherein the distal end carries the body.
10. A device according to claim 1
and further including a source of therapeutic substance arranged
for compaction by the body into cancellous bone compressed by the
body.
Description
This invention relates to improvements in the surgical treatment of
bone conditions of the human and other animal bone systems and,
more particularly, to an inflatable balloon-like device for use in
treating such bone conditions.
Osteoporosis, avascular necrosis and bone cancer are diseases of
bone that predispose the bone to fracture or collapse. There are 2
million fractures each year in the United States, of which about
1.3 million are caused by osteoporosis, while avascular necrosis
and bone cancers are more rare. These conditions cause bone
problems that have been poorly addressed, resulting in deformities
and chronic complications.
The outcome of many other orthopedic procedures to treat bone, such
as open surgeries involving infected bone, poorly healing bone or
bone fractured by severe trauma, can also be improved. Currently,
bone is prepared to receive materials such as bone graft or bone
substitutes by removing diseased or injured bone using standard
tools, usually made of metal. Gaps between the patient's remaining
bone and the inserted materials delay or prevent healing.
Therapeutic substances like antibiotics and bone growth factors
have not been applied to bone in a way that optimizes and maintains
their contact with the desired area of bone. Antibiotics, bone
growth factors and other drugs can prevent complications and hasten
repair. They are currently placed as dry powders or liquids around
the treated bone, or else are formulated into a gel or a degradable
plastic polymer and inserted into areas with defects (holes in the
bone). Delivered in this manner, they can be washed away by blood
or other fluids, either immediately or as their carrier degrades.
Also, the amount of therapeutic substance delivered in a gel or
polymer can be limited by the space provided by the defect.
BACKGROUND OF THE INVENTION
In U.S. Pat. Nos. 4,969,888 and 5,108,404, an apparatus and method
are disclosed for the fixation of fractures or other conditions of
human and other animal bone systems, both osteoporotic and
non-osteoporotic. The apparatus and method are especially suitable
for, but not limited to, use in the fixation of vertebral body
compression fractures, Colles fractures and fractures of the
proximal humerus.
The method disclosed in these two patents includes a series of
steps in which a surgeon or health care provider can perform to
form a cavity in fractured or pathological bone (including but not
limited to osteoporotic bone, osteoporotic fractured metaphyseal
and epiphyseal bone, osteoporotic vertebral bodies, fractured
osteoporotic vertebral bodies, fractures of vertebral bodies due to
tumors especially round cell tumors, avascular necrosis of the
epiphyses of long bones, especially avascular necrosis of the
proximal femur, distal femur and proximal humerus and defects
arising from endocrine conditions).
The method further includes an incision in the skin (usually one
incision, but a second small incision may also be required if a
suction egress is used) followed by the placement of a guide pin
which is passed through the soft tissue down to and into the
bone.
The method further includes drilling the bone to be treated to form
a cavity or passage in the bone, and inserting an inflatable
balloon-like device into the cavity or passage. Inflation of the
inflatable device causes a compacting of the cancellous bone and
bone marrow against the inner surface of the cortical wall of the
bone to further enlarge the cavity or passage. The inflatable
device is then deflated and then is completely removed from the
bone. A smaller inflatable device (a starter balloon) can be used
initially, if needed, to initiate the compacting of the bone marrow
and to commence the formation of the cavity or passage in the
cancellous bone and marrow. After this has occurred, a larger,
inflatable device is inserted into the cavity or passage to further
compact the bone marrow in all directions.
A flowable biocompatible filling material, such as
methylmethacrylate cement or a synthetic bone substitute, is then
directed into the cavity or passage and allowed to set to a
hardened condition to provide structural support for the bone.
Following this latter step, the insertion instruments are removed
from the body and the incision in the skin is covered with a
bandage.
While the apparatus and method of the above patents provide an
adequate protocol for the fixation of bone, it has been found that
the compacting of the bone marrow and/or the trabecular bone and/or
cancellous bone against the inner surface of the cortical wall of
the bone to be treated can be significantly improved with the use
of inflatable devices that incorporate additional engineering
features not heretofore described and not properly controlled with
prior inflatable devices in such patents. It has also been found
that therapeutic substances can be delivered with the apparatus and
methods of the above patents in an unexpected way. It has been
additionally found that the apparatus and methods of the above
patents can be adapted in ways not previously described to improve
open surgeries to fix, fuse or remove bone, as well as to deliver
therapeutic substances during these surgeries. A need has therefore
arisen for improvements in the shape, construction and size of
inflatable devices for use with the foregoing apparatus and method,
as well as for new methods, and the present invention satisfies
such need.
Prior Techniques For The Manufacture Of Balloons For In-Patient
Use
A review of the prior art relating to the manufacture of balloons
shows that a fair amount of background information has been amassed
in the formation of guiding catheters which are introduced into
cardiovascular systems of patients through the brachial or femoral
arteries. However, there is a scarcity of disclosures relating to
inflatable devices used in bone, and none for compacting bone
marrow in vertebral bodies and long bones.
In a dilatation catheter, the catheter is advanced into a patient
until a balloon is properly positioned across a lesion to be
treated. The balloon is inflated with a radiopaque liquid at
pressures above four atmospheres to compress the plaque of the
lesion to thereby dilate the lumen of the artery. The balloon can
then be deflated, then removed from the artery so that the blood
flow can be restored through the dilated artery.
A discussion of such catheter usage technique is found and clearly
disclosed in U.S. Pat. No. 5,163,989. Other details of angioplasty
catheter procedures, and details of balloons used in such
procedures can be found in U.S. Pat. Nos. 4,323,071, 4,332,254,
4,439,185, 4,168,224, 4,516,672, 4,538,622, 4,554,929, and
4,616,652.
Extrusions have also been made to form prism shaped balloons using
molds which require very accurate machining of the interior surface
thereof to form acceptable balloons for angioplastic catheters.
However, this technique of extrusion forms parting lines in the
balloon product which parting lines are limiting in the sense of
providing a weak wall for the balloon itself.
U.S. Pat. No. 5,163,989 discloses a mold and technique for molding
dilatation catheters in which the balloon of the catheter is free
of parting lines. The technique involves inflating a plastic member
of tubular shape so as to press it against the inner molding
surface which is heated. Inflatable devices are molded into the
desired size and shape, then cooled and deflated to remove it from
the mold. The patent states that, while the balloon of the present
invention is especially suitable for forming prism-like balloons,
it can also be used for forming balloons of a wide variety of sizes
and shapes.
A particular improvement in the catheter art with respect to this
patent, namely U.S. Pat. No. 4,706,670, is the use of a coaxial
catheter with inner and outer tubing formed and reinforced by
continuous helical filaments. Such filaments cross each other
causing the shaft of the balloon to become shorter in length while
the moving portion of the shank becomes longer in length. By
suitably balancing the lengths and the angle of the weave of the
balloon and moving portions of the filaments, changes in length can
be made to offset each other. Thus, the position of the inner and
outer tubing can be adjusted as needed to keep the balloon in a
desired position in the blood vessel.
Other disclosures relating to the insertion of inflatable devices
for treating the skeleton of patients include the following:
U.S. Pat. No. 4,313,434 relates to the fixation of a long bone by
inserting a deflated flexible bladder into a medullary cavity,
inflating the balloon bladder, sealing the interior of the long
bone until healing has occurred, then removing the bladder and
filling the opening through which the bladder emerges from the long
bone.
U.S. Pat. No. 5,102,413 discloses the way in which an inflatable
bladder is used to anchor a metal rod for the fixation of a
fractured long bone.
Other references which disclose the use of balloons and cement for
anchoring of a prosthesis include U.S. Pat. Nos. 5,147,366,
4,892,550, 4,697,584, 4,562,598, and 4,399,814.
A Dutch patent, NL 901858, discloses a means for fracture repair
with a cement-impregnated bag which is inflated into a preformed
cavity and allowed to harden.
It can be concluded from the foregoing review of the prior art that
there is little or no substantive information on inflatable devices
used to create cavities in bone. It does not teach the shape of the
balloon which creates a cavity that best supports the bone when
appropriately filled. It does not teach how to prevent balloons
from being spherical when inflated, when this is desired. Current
medical balloons can compress bone but are too small and generally
have the wrong configuration and are generally not strong enough to
accomplish adequate cavity formation in either the vertebral bodies
or long bones of the body.
U.S. Pat. Nos. 4,969,888 and 5,108,404 disclose a checker-shaped
balloon for compressing cancellous bone, but does not provide
information on how this balloon remains in its shape when inflated.
It also does not provide methods to deliver an enhanced supply of
therapeutic agent.
U.S. Pat. No. 4,892,550 describes an elastic balloon for anchoring
a metal prosthesis inside of a bone. U.S. Pat. No. 4,313,434
describes a deflatable bladder to substitute for metal rods which
are placed inside the intramedullary cavity of fractured long bones
(thigh, leg and arm) to keep them together while they heal.
Thus, the need continues for an improved inflatable device and
methods for use with fractured and/or pathological bones.
SUMMARY OF THE INVENTION
The present invention is directed to a balloon-like inflatable
device or balloon for use in carrying out the apparatus and method
of the above-mentioned patents 4,969,888 and 5,108,404, and to new
methods for using these devices, and to new uses of the methods and
devices. Such inflatable devices, hereinafter sometimes referred to
as balloons, have shapes for compressing cancellous bone and marrow
(also known as medullary bone or trabecular bone) against the inner
cortex of bones whether the bones are fractured or not.
In particular, the present invention is directed to a balloon for
use in treating a bone predisposed to fracture or to collapse. The
balloon comprises an inflatable, non-expandable balloon body for
insertion into said bone. The body has a predetermined shape and
size when substantially inflated sufficient to compress at least a
portion of the inner cancellous bone to create a cavity in the
cancellous bone and to restore the original position of the outer
cortical bone, if fractured or collapsed. The balloon body is
restrained to create said predetermined shape and size so that the
fully inflated balloon body is prevented from applying substantial
pressure to the inner surface of the outer cortical bone if said
bone is unfractured or uncollapsed. Substantial pressure is defined
herein as pressure sufficient to displace the cortical cone beyond
its normal configuration.
In addition to the shape of the inflatable device itself, another
aspect of importance is the construction of the wall or walls of
the balloon such that proper inflation the balloon body is achieved
to provide for optimum compression of all the bone marrow. The
material of the balloon is also desirably chosen so as to be able
to fold the balloon so that it can be inserted quickly and easily
into a bone using a guide pin and a canula, yet can also withstand
high pressures when inflated. The balloon can also include optional
ridges or indentations which are left in the cavity after the
balloon has been removed, to enhance the stability of the filler.
Also, the inflatable device can be made to have an optional,
built-in suction catheter. This is used to remove any fat or fluid
extruded from the bone during balloon inflation in the bone. Also,
the balloon body can be protected from puncture by the cortical
bone or canula by being covered while inside the canula with an
optional protective sleeve of suitable material, such as Kevlar or
PET or other polymer or substance that can protect the balloon. A
main purpose of the inflatable device, therefore, is the forming or
enlarging of a cavity or passage in a bone, especially in, but not
limited to, vertebral bodies.
In one aspect, the invention provides an improved balloon-like
inflatable device for use in carrying out a surgical protocol of
cavity formation in bones to enhance the efficiency of the
protocol, to minimize the time prior to performing the surgery for
which the protocol is designed and to improve the clinical outcome.
These balloons approximate the inner shape of the bone they are
inside of in order to maximally compress cancellous bone. They have
additional design elements to achieve specific clinical goals.
Preferably, they are made of inelastic material and kept in their
defined configurations when inflated, by various restraints,
including (but not limited to) use of inelastic materials in the
balloon body, seams in the balloon body created by bonding or
fusing separate pieces of material together, or by fusing or
bonding together opposing sides of the balloon body, woven material
bonded inside or outside the balloon body, strings or bands placed
at selected points in the balloon body, and stacking balloons of
similar or different sizes or shapes on top of each other by gluing
or by heat fusing them together. Optional ridges or indentations
created by the foregoing structures, or added on by bonding
additional material, increases stability of the filler. Optional
suction devices, preferably placed so that if at least one hole is
in the lowest point of the cavity being formed, will allow the
cavity to be cleaned before filling.
In another aspect, the invention provides new uses for these
balloons, and new methods for their use. Balloons can be used to
deliver therapeutic substances by coating the balloons with the
therapeutic substance before inserting the balloon into bone. When
coated balloons are inflated in bone, the therapeutic substances
are pressed into the cancellous bone while that bone is being
compressed by the balloon. This allows desired amounts of the
therapeutic substance to be delivered directly to the site of
therapy in a manner that is maintained over time. The balloons can
also be used during minimally invasive or open surgeries to provide
an improved space for orthopedic implants, bone graft, bone
substitutes, acrylic cements, bone fillers, bone growth factors,
chemotherapeutic agents, antibiotics or other drugs. The agents
inside the bone can be intended to treat the bone itself or to
serve as a reservoir of drug for a structure nearby, such as an
osteosarcoma.
In yet another aspect of the invention, the balloons can be used to
temporarily provide structural support for a fractured or diseased
bone. In this embodiment, the fractured or diseased bone can be
treated by inflating the balloon at the treatment site and leaving
it in place until the surrounding cortical bone heals. In other
words, the balloon will take the place of the biocompatible filling
material used in previous methods to support the fractured or
diseased bone. The invention will include a mechanism for sealing
the inflated balloon outside of the bone cavity, but within the
patient. The sealing mechanism can include a metal or plastic clip,
a check valve activated by unscrewing the inflation tube, a plug
for sealing the inner passage of the balloon or the like. Similar
to previous embodiments, the balloon will be delivered into the
bone and inflated to compress the inner cancellous bone and create
a cavity therein. The inflated balloon will then be sealed, e.g.,
by inserting a plug within the inflation opening, the inflation
tube will be removed from the patient, and the percutaneous
incision will be closed. The fluid pressure within the balloon
provides sufficient support for the bone to allow the bone to heal.
The balloon can be left in the bone cavity in the inflated
configuration for an amount of time necessary for the outer
cortical bone to completely or at least partially heal, usually
about 1 day to 3 months and preferably about 6-8 weeks. In this
aspect of the invention, the balloon is providing at least four
functions: (1) realigning the bones; (2) eliminating or at least
reducing diseased inner cancellous bone; (3) strengthening the
outer cortical bone by providing additional calcium from the
compressed inner cancellous bone which is incorporated into the
outer cortical bone as it heals; and (4) acting as an internal cast
while the cortical bone heals.
After the cortical bone has healed, the surgeon can access the
balloon through the same or another percutaneous incision to
deflate the balloon by removing the clip, plug or, in the case of a
check valve, by screwing the inflation tube back into the balloon.
In many cases, the cortical bone will have become sufficiently
strengthened through healing with additional calcium from the
compressed cancellous. In these cases, the balloon will be removed
from the bone cavity. The balloon may include a coating, such as
Gelfoam or an antibiotic, on its outer surface to stop bleeding,
prevent infection, minimize bone growth into the balloon and/or to
facilitate separation of the balloon from the bone when the balloon
is deflated. If, however, the surgeon determines that the cortical
bone is still too weak (e.g., through a bone density scan or other
measurement), appropriate supporting material, such as acrylic
cements, bone substitutes, bone fillers or bone growth factors, can
be inserted into the bone cavity before removal of the balloon.
The methods of the above-mentioned patents and the improvements
herein can be applied anywhere in the skeleton where there is
cancellous and/or trabecular and/or medullary bone.
Among the various embodiments of the present invention are the
following:
1. A doughnut (or torus) shaped balloon with an optional built-in
suction catheter to remove fat and other products extruded during
balloon expansion.
2. A balloon with a spherical outer shape surrounded by a
ring-shaped balloon segment for body cavity formation.
3. A balloon which is kidney bean shaped in configuration. Such a
balloon can be constructed in a single layer, or several layers
stacked on top of each other. This embodiment can also be a square
or a rectangle instead of a kidney bean.
4. A spherically shaped balloon approximating the size of the head
of the femur (i.e. the proximal femoral epiphysis). Such a balloon
can also be a hemisphere.
5. A balloon in the shape of a humpbacked banana or a modified
pyramid shape approximating the configuration of the distal end of
the radius (i.e. the distal radial epiphysis and metaphysis).
6. A balloon in the shape of a cylindrical ellipse to approximate
the configuration of either the medial half or the lateral half of
the proximal tibial epiphysis. Such a balloon can also be
constructed to approximate the configuration of both halves of the
proximal tibial epiphysis.
7. A balloon in the shape of sphere on a base to approximate the
shape of the proximal humeral epiphysis and metaphysis with a plug
to compress cancellous bone into the diaphysis, sealing it off.
Such an embodiment can also be a cylinder.
8. A balloon in the shape of a boomerang to approximate the inside
of the femoral head, neck and lesser trochanter, allowing a
procedure to prevent hip fracture.
9. A balloon in the shape of a cylinder to approximate the size and
shape of the inside of the proximal humerus or of the distal
radius.
10. A balloon device with an optional suctional device. and
11. Protective sheaths to act as puncture guard members optionally
covering each balloon inside its catheter.
The present invention, therefore, provides improved, inflatable
devices for creating or enlarging a cavity or passage in a bone
wherein the devices are inserted into the bone. The configuration
of each device is defined by the surrounding cortical bone and
adjacent internal structures, and is designed to occupy about
70-90% of the volume of the inside of the bone, although balloons
that are as small as about 40% and as large as about 99% are
workable for fractures. In certain cases, usually avascular
necrosis, the balloon size may be as small as 10% of the cancellous
bone volume of the area of bone being treated, due to the localized
nature of the fracture or collapse. The fully expanded size and
shape of the balloon is limited by additional material in selected
portions of the balloon body whose extra thickness creates a
restraint as well as by either internal or external restraints
formed in the device including, but not limited to, mesh work, a
winding or spooling of material laminated to portions of the
balloon body, continuous or non-continuous strings across the
inside held in place at specific locations by glue inside or by
threading them through to the outside and seams in the balloon body
created by bonding two pieces of body together or by bonding
opposing sides of a body through glue or heat. Spherical portions
of balloons may be restrained by using inelastic materials in the
construction of the balloon body, or may be additionally restrained
as just described. The material of the balloon is preferably a
non-elastic material, such as polyethylene tetraphthalate (PET),
Kevlar or other patented medical balloon materials. It can also be
made of semi-elastic materials, such as silicone or elastic
material such as latex, if appropriate restraints are incorporated.
The restraints can be made of a flexible, inelastic high tensile
strength material including, but not limited, to those described in
U.S. Pat. No. 4,706,670. The thickness of the balloon wall is
typically in the range of 2/1000ths to 25/1000ths of an inch, or
other thicknesses that can withstand pressures of up to 250-400
psi.
One important goal of percutaneous vertebral body augmentation of
the present invention is to provide a balloon which can create a
cavity inside the vertebral body whose configuration is optimal for
supporting the bone. Another important goal is to move the top of
the vertebral body back into place to retain height where possible,
however, both of these objectives must be achieved without changing
the outer diameter of the sides of the vertebral body, either by
fracturing the cortical wall of the vertebral body or by moving
already fractured bone. This feature could push vertebral bone
toward the spinal cord, a condition which is not to be desired.
The present invention satisfies these goals through the design of
inflatable devices to be described. Inflating such a device
compresses the calcium-containing soft cancellous bone into a thin
shell that lines the inside of the hard cortical bone creating a
large cavity.
At the same time, the biological components (red blood cells, bone
progenitor cells) within the soft bone are pressed out and removed
by rinsing during the procedure. The body recreates the shape of
the inside of an unfractured vertebral body, but optimally stops at
approximately 70 to 90% of the inner volume. The balloons of the
present invention are inelastic, so maximally inflating them can
only recreate the predetermined shape and size. However,
conventional balloons become spherical when inflated. Spherical
shapes will not allow the hardened bone cement to support the spine
adequately, because they make single points of contact on each
vertebral body surface (the equivalent of a circle inside a square,
or a sphere inside a cylinder). The balloons of the present
invention recreate the flat surfaces of the vertebral body by
including restraints that keep the balloon in the desired shape.
This maximizes the contacts between the vertebral body surfaces and
the bone cement, which strengthens the spine. In addition, the
volume of bone cement that fills these cavities creates a thick
mantle of cement (4 mm or greater), which is required for
appropriate compressive strength. Another useful feature, although
not required, are ridges in the balloons which leave their imprint
in the lining of compressed cancellous bone. The resulting bone
cement "fingers" provide enhanced stability.
The balloons which optimally compress cancellous bone in vertebral
bodies are the balloons listed as balloon types 1, 2 and 3 above.
These balloons are configured to approximate the shape of the
vertebral body. Since the balloon is chosen to occupy 70 to 90% of
the inner volume, it will not exert undue pressure on the sides of
the vertebral body, thus the vertebral body will not expand beyond
its normal size (fractured or unfractured). However, since the
balloon has the height of an unfractured vertebral body, it can
move the top, which has collapsed, back to its original position.
Any number of individual balloons can be stacked, and stacks
containing any of the balloons of types 1, 2 and 3 can be mixed in
shape and/or size to provide greater flexibility and/or
control.
A primary goal of percutaneous proximal humeral augmentation is to
create a cavity inside the proximal humerus whose configuration is
optimal for supporting the proximal humerus. Another important goal
is to help realign the humeral head with the shaft of the humerus
when they are separated by a fracture. Both of these goals must be
achieved by exerting pressure primarily on the cancellous bone, and
not the cortical bone. Undue pressure against the cortical bone
could conceivably cause a worsening of a shoulder fracture by
causing cortical bone fractures.
The present invention satisfies these goals through the design of
the inflatable devices to be described. Inflating such a device
compresses the cancellous bone against the cortical walls of the
epiphysis and metaphysis of the proximal humerus thereby creating a
cavity. In some cases, depending on the fracture location, the
balloon or inflatable device may be used to extend the cavity into
the proximal part of the humeral diaphysis.
Due to the design of the "sphere on a stand" balloon (described as
number 7 above), the cavity made by this balloon recreates or
approximates the shape of the inside cortical wall of the proximal
humerus. The approximate volume of the cavity made by the
"spherical on a stand balloon" is 70 to 90% that of the proximal
humeral epiphysis and metaphysis, primarily, but not necessarily
exclusive of, part of the diaphysis. The shape approximates the
shape of the humeral head. The "base" is designed to compress the
trabecular bone into a "plug" of bone in the distal metaphysis or
proximal diaphysis. This plug of bone will prevent the flow of
injectable material into the shaft of the humerus, improving the
clinical outcome. The sphere can also be used without a base.
Alternatively, the balloon can be shaped like a fat cylinder, with
one end at the top of the humeral head attached to the catheter and
the other end filling the function of the plug. The cylinder can
also be formed so that the diameter of the end in the humerus is
greater than the diameter of the end which functions as the
plug.
A primary goal of percutaneous distal radius augmentation is to
create a cavity inside the distal radius whose configuration is
optimal for supporting the distal radius. Another important goal is
to help fine tune fracture realignment after the fracture has been
partially realigned by finger traps. Both of these goals must be
achieved by exerting pressure primarily on the cancellous bone and
not on the cortical bone. Excessive pressure against the cortical
bone could conceivably cause cortical bone fractures, thus
worsening the condition.
The present invention satisfies these goals through the design of
inflatable devices either already described or to be described.
The design of the "humpbacked banana", or modified pyramid design
(as described as number 5 above), approximates the shape of the
distal radius and therefore, the cavity made by this balloon
approximates the shape of the distal radius as well. The
approximate volume of the cavity to be made by this humpbacked
banana shaped balloon is 70 to 90% that of the distal radial
epiphysis and metaphysis primarily of, but not necessarily
exclusive of, some part of the distal radial diaphysis. Inflating
such a device compresses the cancellous bone against the cortical
walls of the epiphysis and metaphysis of the distal radius in order
to create a cavity. In some cases, depending on the fracture
location, the osseous balloon or inflatable device may be used to
extend the cavity into the distal part of the radial diaphysis.
A primary goal of percutaneous femoral head (or humeral head)
augmentation is to create a cavity inside the femoral head (or
humeral head) whose configuration is optimal for supporting the
femoral head. Another important goal is to help compress avascular
(or aseptic) necrotic bone or support avascular necrotic bone in
the femoral head. This goal may include the realignment of
avascular bone back into the position it previously occupied in the
femoral head in order to improve the spherical shape of the femoral
head. These goals must be achieved by exerting pressure primarily
on the cancellous bone inside the femoral head.
The present invention satisfied these goals through the design of
inflatable devices either already described or to be described.
The design of the spherical osseous balloon (described as balloon
type 4 above) approximates the shape of the femoral head and
therefore creates a cavity which approximates the shape of the
femoral head as well. (It should be noted that the spherical shape
of this inflatable device also approximates the shape of the
humeral head and would, in fact, be appropriate for cavity
formation in this osseous location as well.) Inflating such a
device compresses the cancellous bone of the femoral head against
its inner cortical walls in order to create a cavity. In some
cases, depending upon the extent of the avascular necrosis, a
smaller or larger cavity inside the femoral head will be formed. In
some cases, if the area of avascular necrosis is small, a small
balloon will be utilized which might create a cavity only 10 to 15%
of the total volume of the femoral head. If larger areas of the
femoral head are involved with the avascular necrosis, then a
larger balloon would be utilized which might create a much larger
cavity, approaching 80 to 90% of the volume of the femoral
head.
The hemispherical balloon approximates the shape of the top half of
the femoral (and humeral) head, and provides a means for compacting
cancellous bone in an area of avascular necrosis or small fracture
without disturbing the rest of the head. This makes it easier to do
a future total joint replacement if required.
Percutaneous hip augmentation is designed to prevent hip fracture
by compacting weak cancellous bone in the femur where hip fractures
occur and replacing it with appropriate supporting material. A
primary goal of percutaneous hip augmentation is to create a cavity
inside the femoral head, femoral neck and lesser trochanter which
will compress diseased cancellous bone and allow it to be replaced
with appropriate supporting material, preventing hip fracture. The
cavity created by the procedure usually extends from the femoral
head, past the lesser trochanter by a defined amount, but generally
not further. The cavity should not expand into the greater
trochanter, where hip fractures do not affect the patient, because
this may prevent the balloon from expanding into the lesser
trochanter, where hip fractures do affect the patient. The balloon
should compact the cancellous bone as fully as possible without
pushing the inner cortical bone, which could cause (instead of
prevent) a fracture.
The present invention satisfies these goals by providing inflatable
devices to be described and which have special features, including
their placement on the catheter, to orient the balloon
appropriately.
A primary goal of percutaneous proximal tibial augmentation is to
create a cavity inside the proximal tibia whose configuration is
optimal for supporting either the medial or lateral tibial
plateaus. Another important goal is to help realign the fracture
fragments of tibial plateau fractures, particularly those features
with fragments depressed below (or inferior to) their usual
location. Both of these objectives must be achieved by exerting
pressure on primarily the cancellous bone and not the cortical
bone. Pressure on the cortical bone could conceivably cause
worsening of the tibial plateau fracture.
The present invention satisfies these goals through the design of
the inflatable devices to be described. Inflating such a device
compresses the cancellous bone against the cortical walls of the
medial or lateral tibial plateau in order to create a cavity.
Due to the design of the "elliptical cylinder" balloon (described
as balloon type 6 above) the cavity made by this balloon recreates
or approximates the shape of the cortical walls of either the
medial or lateral tibial plateaus. The approximate volume of the
cavity to be made by the appropriate elliptical cylindrical balloon
is 50 to 90% of the proximal epiphyseal bone of either the medial
half or the lateral half of the tibial.
Due to the nature of the injury, disease or other treatments, it
may be preferable to treat a bone with the devices of this
invention during an open surgical procedure. In addition, a goal of
the percutaneous or open surgery may be to replace the diseased or
injured bone with materials (such as bone fillers or certain drugs)
which do not flow.
The present invention satisfies these goals through the systems and
methods of this invention described below.
Other objects of the present invention will become apparent as the
following specification progresses, reference being had to the
accompanying drawings for an illustration of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a first embodiment of the balloon
of the present invention, the embodiment being in the shape of a
stacked doughnut assembly;
FIG. 2 is a vertical section through the balloon of FIG. 1 showing
the way in which the doughnut portions of the balloon of FIG. 1,
fit into a cavity of a vertebral body;
FIG. 3 is a schematic view of another embodiment of the balloon of
the present invention showing three stacked balloons and
string-like restraints for limiting the expansion of the balloon in
directions of inflation;
FIG. 4 is a top plan view of a spherical balloon having a
cylindrical ring surrounding the balloon;
FIG. 5 is a vertical section through the spherical balloon and ring
of FIG. 4;
FIG. 6 shows an oblong-shaped balloon with a catheter extending
into the central portion of the balloon;
FIG. 6A is a perspective view of the way in which a catheter is
arranged relative to the inner tubes for inflating the balloon of
FIG. 6;
FIG. 7 is a suction tube and a contrast injection tube for carrying
out the inflation of the balloon and removal of debris caused by
expansion from the balloon itself;
FIG. 8 is a vertical section through a balloon after it has been
deflated and as it is being inserted into the vertebral body of a
human;
FIGS. 9 and 9A are side elevational views of a canula showing how
the protective sleeve or guard member expands when leaving the
canula;
FIG. 9B is a vertical section through a vertebral bone into which
an access hole has been drilled;
FIG. 10 is a perspective view of another embodiment of the balloon
of the present invention formed in the shape of a kidney bean;
FIG. 11 is a perspective view of the vertebral bone showing the
kidney shaped balloon of FIG. 10 inserted in the bone and
expanded;
FIG. 12 is a top view of a kidney shaped balloon formed of several
compartments by a heating element or branding tool;
FIG. 13 is a cross-sectional view taken along line 13--13 of FIG.
12 but with two kidney shaped balloons that have been stacked.
FIG. 14 is a view similar to FIG. 11 but showing the stacked kidney
shaped balloon of FIG. 13 in the vertebral bone;
FIG. 15 is a top view of a kidney balloon showing outer tufts
holding inner strings in place interconnecting the top and bottom
walls of the balloon;
FIG. 16 is a cross sectional view taken along lines 16--16 of FIG.
15;
FIG. 17A is a dorsal view of a humpback banana balloon in a right
distal radius;
FIGS. 17B is a cross sectional view of FIG. 17A taken along line
17B--17B of FIG. 17A;
FIG. 18 is a spherical balloon with a base in a proximal humerus
viewed from the front (anterior) of the left proximal humerus;
FIG. 18A is a cylindrical balloon viewed from the front (anterior)
of the left proximal humerus.
FIG. 19A is the front (anterior) view of the proximal tibia with
the elliptical cylinder balloon introduced beneath the medial
tibial plateau;
FIG. 19B is a three quarter view of the balloon of FIG. 19A;
FIG. 19C is a side elevational view of the balloon of FIG. 19A;
FIG. 19D is a top plan view of the balloon of FIG. 19A;
FIG. 20 is a spherically shaped balloon for treating avascular
necrosis of the head of the femur (or humerus) as seen from the
front (anterior) of the left hip;
FIG. 20A is a side view of a hemispherically shaped balloon for
treating avascular necrosis of the head of the femur (or
humerus);
FIG. 21 is a balloon for preventing hip fracture as seen from the
front (anterior) of the left hip; and
FIGS. 22A-C are schematic illustrations of a representative method
and system for delivering a therapeutic substance to a bone
according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Balloons For Vertebral Bodies
A first embodiment of the balloon (FIG. 1) of the present invention
is broadly denoted by the numeral 10 and includes a balloon body 11
having a pair of hollow, inflatable, non-expandable parts 12 and 14
of flexible material, such as PET or Kevlar. Parts 12 and 14 have a
suction tube 16 therebetween for drawing fats and other debris by
suction into tube 16 for transfer to a remote disposal location.
Catheter 16 has one or more suction holes so that suction may be
applied to the open end of tube 16 from a suction source (not
shown).
The parts 12 and 14 are connected together by an adhesive which can
be of any suitable type. Parts 12 and 14 are doughnut-shaped as
shown in FIG. 1 and have tubes 18 and 20 which communicate with and
extend away from the parts 12 and 14, respectively, to a source of
inflating liquid under pressure (not shown). The liquid can be any
sterile biocompatible solution. The liquid inflates the balloon 10,
particularly parts 12 and 14 thereof after the balloon has been
inserted in a collapsed condition (FIG. 8) into a bone to be
treated, such as a vertebral bone 22 in FIG. 2. The above-mentioned
U.S. Pat. Nos. 4,969,888 and 5,108,404 disclose the use of a guide
pin and canula for inserting the balloon into bone to be treated
when the balloon is deflated and has been inserted into a tube and
driven by the catheter into the cortical bone where the balloon is
inflated.
FIG. 8 shows a deflated balloon 10 being inserted through a canula
26 into bone. The balloon in canula 26 is deflated and is forced
through the canula by exerting manual force on the catheter 21
which extends into a passage 28 extending into the interior of the
bone. The catheter is slightly flexible but is sufficiently rigid
to allow the balloon to be forced into the interior of the bone
where the balloon is then inflated by directing fluid into tube 88
whose outlet ends are coupled to respective parts 12 and 14.
In use, balloon 10 is initially deflated and, after the bone to be
filled with the balloon has been prepared to receive the balloon
with drilling, the deflated balloon is forced into the bone in a
collapsed condition through canula 26. The bone is shown in FIG. 2.
The balloon is oriented preferably in the bone such that it allows
minimum pressure to be exerted on the bone marrow and/or cancellous
bone if there is no fracture or collapse of the bone. Such pressure
will compress the bone marrow and/or cancellous bone against the
inner wall of the cortical bone, thereby compacting the bone marrow
of the bone to be treated and to further enlarge the cavity in
which the bone marrow is to be replaced by a biocompatible,
flowable bone material.
The balloon is then inflated to compact the bone marrow and/or
cancellous bone in the cavity and, after compaction of the bone
marrow and/or cancellous bone, the balloon is deflated and removed
from the cavity. While inflation of the balloon and compaction
occurs, fats and other debris are sucked out of the space between
and around parts 12 and 14 by applying a suction force to catheter
tube 16. Following this, and following the compaction of the bone
marrow, the balloon is deflated and pulled out of the cavity by
applying a manual pulling force to the catheter tube 21.
The second embodiment of the inflatable device of the present
invention is broadly denoted by the numeral 60 and is shown in
FIGS. 4 and 5. Balloon 60 includes a central spherical part 62
which is hollow and which receives an inflating liquid under
pressure through a tube 64. The spherical part is provided with a
spherical outer surface 66 and has an outer periphery which is
surrounded substantially by a ring shaped part 68 having tube
segments 70 for inflation of part 68. A pair of passages 69
interconnect parts 62 and 68. A suction tube segment 72 draws
liquid and debris from the bone cavity being formed by the balloon
60.
Provision can be made for a balloon sleeve 71 for balloon 60 and
for all balloons disclosed herein. A balloon sleeve 71 (FIG. 9) is
displaceably mounted in an outer tube 71a and can be used to insert
the balloon 60 when deflated into a cortical bone. The sleeve 71
has resilient fingers 71b which bear against the interior of the
entrance opening 71c of the vertebral bone 22 (FIG. 9A) to prevent
tearing of the balloon. Upon removal of the balloon sleeve, liquid
under pressure will be directed into tube 64 which will inflate
parts 62 and 68 so as to compact the bone marrow within the
cortical bone. Following this, balloon 60 is deflated and removed
from the bone cavity.
FIGS. 6 and 6A show several views of a modified doughnut shape
balloon 80 of the type shown in FIGS. 1 and 2, except the doughnut
shapes of balloon 80 are not stitched onto one another. In FIG. 6,
balloon 80 has a pear-shaped outer convex surface 82 which is made
up of a first hollow part 84 and a second hollow part 85. A tube 88
is provided for directing liquid into the two parts along branches
90 and 92 to inflate the parts after the parts have been inserted
into the medullary cavity of a bone. A catheter tube 16 is inserted
into the space 96 between two parts of the balloon 80. An adhesive
bonds the two parts 84 and 85 together at the interface
thereof.
FIG. 6A shows the way in which the catheter tube 16 is inserted
into the space or opening 96 between the two parts of the balloon
80.
FIG. 7 shows tube 88 of which, after directing inflating liquid
into the balloon 80, can inject contrast material into the balloon
80 so that x-rays can be taken of the balloon with the inflating
material therewithin to determine the proper placement of the
balloon. Tube 16 is also shown in FIG. 6, it being attached in some
suitable manner to the outer side wall surface of tube 88.
Still another embodiment of the invention is shown in FIG. 3 which
is similar to FIG. 1 except that it is round and not a doughnut and
includes an inflatable device 109 having three balloon units 110,
112 and 114 which are inflatable and which have string-like
restraints 117 which limit the expansion of the balloon units in a
direction transverse to the longitudinal axes of the balloon units.
The restraints are made of the same or similar material as that of
the balloon so that they have some resilience but substantially no
expansion capability.
A tube system 115 is provided to direct liquid under pressure into
balloon units 110, 112 and 114 so that liquid can be used to
inflate the balloon units when placed inside the bone in a deflated
state. Following the proper inflation and compaction of the bone
marrow, the balloon can be removed by deflating it and pulling it
outwardly of the bone being treated. The restraints keep the
opposed sides 77 and 79 substantially flat and parallel with each
other.
In FIG. 10, another embodiment of the inflatable balloon is shown.
The device is a kidney shaped balloon body 130 having a pair of
opposed kidney shaped side walls 132 which are adapted to be
collapsed and to cooperate with a continuous end wall 134 so that
the balloon 130 can be forced into a bone 136 shown in FIG. 11. A
tube 138 is used to direct inflating liquid into the balloon to
inflate the balloon and cause it to assume the dimensions and
location shown vertebral body 136 in FIG. 11. Device 130 will
compress the cancellous bone if there is no fracture or collapse of
the cancellous bone. The restraints for this action are due to the
side and end walls of the balloon.
FIG. 12 shows a balloon 140 which is also kidney shaped and has a
tube 142 for directing an inflatable liquid into the tube for
inflating the balloon. The balloon is initially a single chamber
bladder but the bladder can be branded along curved lines or strips
141 to form attachment lines 144 which take the shape of
side-by-side compartments 146 which are kidney shaped as shown in
FIG. 13. A similar pattern of strips as in 140 but in straight
lines would be applied to a balloon that is square or rectangular.
The branding causes a welding of the two sides of the bladder to
occur since the material is standard medical balloon material,
which is similar to plastic and can be formed by heat.
FIG. 14 is a perspective view of a vertebral body 147 containing
the balloon of FIG. 12, showing a double stacked balloon 140 when
it is inserted in vertebral bone 147.
FIG. 15 is a view similar to FIG. 10 except that tufts 155, which
are string-like restraints, extend between and are connected to the
side walls 152 of inflatable device 150 and limit the expansion of
the side walls with respect to each other, thus rendering the side
walls generally parallel with each other. Tube 88 is used to fill
the kidney shaped balloon with an inflating liquid in the manner
described above.
The dimensions for the vertebral body balloon will vary across a
broad range. The heights (H, FIG. 11) of the vertebral body balloon
for both lumbar and thoracic vertebral bodies typically range from
0.5 cm to 3.5 cm. The anterior to posterior (A, FIG. 11) vertebral
body balloon dimensions for both lumbar and thoracic vertebral
bodies range from 0.5 cm to 3.5 cm. The side to side (L, FIG. 11)
vertebral body dimensions for thoracic vertebral bodies will range
from 0.5 cm to 3.5 cm. The side to side vertebral body dimensions
for lumbar vertebral bodies will range from 0.5 cm to 5.0 cm. An
optimal vertebral body balloon is stacked with two or more members
of unequal height where each member can be separately inflated
through independent tube systems. The total height of the stack
when fully inflated should be within the height ranges specified
above. Such a design allows the fractured vertebral body to be
returned to its original height in steps, which can be easier on
the surrounding tissue, and it also allows the same balloon to be
used in a wider range of vertebral body sizes.
The eventual selection of the appropriate balloon for, for
instance, a given vertebral body is based upon several factors. The
anterior-posterior (A-P) balloon dimension for a given vertebral
body is selected from the CT scan or plain film x-ray views of the
vertebral body. The A-P dimension is measured from the internal
cortical wall of the anterior cortex to the internal cortical wall
of the posterior cortex of the vertebral body. In general, the
appropriate A-P balloon dimension is 5 to 7 millimeters less than
this measurement.
The appropriate side to side balloon dimensions for a given
vertebral body is selected from the CT scan or from a plain film
x-ray view of the vertebral body to be treated. The side to side
distance is measured from the internal cortical walls of the side
of the vertebral bone. In general, the appropriate side to side
balloon dimension is 5 to 7 millimeters less than this measurement
by the addition of the lumbar vertebral body tends to be much wider
than side to side dimension then their A-P dimension. In thoracic
vertebral bodies, the side to side dimension and their A-P
dimensions are almost equal.
The height dimensions of the appropriate vertebral body balloon for
a given vertebral body is chosen by the CT scan or x-ray views of
the vertebral bodies above and below the vertebral body to be
treated. The height of the vertebral bodies above and below the
vertebral body to be treated are measured and averaged. This
average is used to determine the appropriate height dimension of
the chosen vertebral body balloon.
Balloons For Long Bones
Long bones which can be treated with the use of balloons of the
present invention include distal radius (larger arm bone at the
wrist), proximal tibial plateau (leg bone just below the knee),
proximal humerus (upper end of the arm at the shoulder), and
proximal femoral head (leg bone in the hip).
Distal Radius Balloon
For the distal radius, a balloon 160 is shown in the distal radius
152 and the balloon has a shape which approximates a pyramid but
more closely can be considered the shape of a humpbacked banana in
that it substantially fills the interior of the space of the distal
radius to force cancellous bone 154 lightly against the inner
surface 156 of cortical bone 158. Note that the spherical radius
balloon discussed above may also be appropriately sized for the
distal radius 152.
The balloon 160 has a lower, conical portion 159 which extends
downwardly into the hollow space of the distal radius 152, and this
conical portion 159 increases in cross section as a central distal
portion 161 is approached. The cross section of the balloon 160 is
shown at a central location (FIG. 17B) and this location is near
the widest location of the balloon. The upper end of the balloon,
denoted by the numeral 162, converges to the catheter 88 for
directing a liquid into the balloon for inflating the same to force
the cancellous bone against the inner surface of the cortical bone.
The shape of the balloon 160 is determined and restrained by tufts
formed by string restraints 165. These restraints are optional and
provide additional strength to the balloon body 160, but are not
required to achieve the desired configuration. The balloon is
placed into and taken out of the distal radius in the same manner
as that described above with respect to the vertebral bone.
The dimensions of the distal radius balloon vary as follows:
The proximal end of the balloon (i.e. the part nearest the elbow)
is cylindrical in shape and will vary from 0.5.times.0.5 cm to
1.8.times.1.8 cm.
The length of the distal radius balloon will vary from 1.0 cm to
12.0 cm.
The widest medial to lateral dimension of the distal radius
balloon, which occurs at or near the distal radio-ulnar joint, will
measure from 1.0 cm to 2.5 cm.
The distal anterior-posterior dimension of the distal radius
balloon will vary from 0.5 to 3.0 cm.
Proximal Humerus Fracture Balloon
The selection of the appropriate balloon size to treat a given
fracture of the distal radius will depend on the radiological size
of the distal radius and the location of the fracture.
In the case of the proximal humerus 169, a balloon 166 shown in
FIG. 18 is spherical and has a base design. It compacts the
cancellous bone 168 in a proximal humerus 169. A mesh 170, embedded
or laminated and/or winding, may be used to form a neck 172 on the
balloon 166, and second mesh 170a may be used to conform the bottom
of the base 172a to the shape of the inner cortical wall at the
start of the shaft. These restraints provide additional strength to
the balloon body, but the configuration can be achieved through
molding of the balloon body. This is so that the cancellous bone
will be as shown in the compacted region surrounding the balloon
166 as shown in FIG. 18. The cortical bone 173 is relatively wide
at the base 174 and is thin-walled at the upper end 175. The
balloon 166 has a feed tube 177 into which liquid under pressure is
forced into the balloon to inflate it to lightly compact the
cancellous bone in the proximal humerus. The balloon is inserted
into and taken out of the proximal humerus in the same manner as
that described above with respect to the vertebral bone.
The dimensions of the proximal humerus fracture balloon vary as
follows:
The spherical end of the balloon will vary from 1.0.times.1.0 cm to
3.0.times.3.0 cm.
The neck of the proximal humeral fracture balloon will vary from
0.8.times.0.8 cm to 3.0.times.3.0 cm.
The width of the base portion or distal portion of the proximal
numeral fracture balloon will vary from 0.5.times.0.5 cm to
2.5.times.2.5 cm.
The length of the balloon will vary from 4.0 cm to 14.0 cm.
The selection of the appropriate balloon to treat a given proximal
humeral fracture depends on the radiologic size of the proximal
humerus and the location of the fracture.
Another balloon adapted for use in the proximal humerus 169 is the
cylindrical balloon 225 shown in FIG. 18A. Like the feed tube 177
of FIG. 18, cylindrical balloon 225 has an inflation tube 226 for
inserting liquid therein. 227 shows the site of a typical shoulder
fracture. The cylinder can have a uniform circumference or it can
be wider at one end than at the other. The wider end would be
attached to the inflating tube 226 to compact the cancellous bone
168 of the humeral head 168a. Appropriate restraints to maintain
the shape include multiple inelastic bands (228 is one of them)
spaced around the circumference at regular intervals. For a
cylinder with a uniform width, the restraining bands will usually
have the same diameter. For a cylinder with one end wider than the
other, each band would successively have a wider diameter.
The length of the balloon is usually the same as that of the sphere
on the base, preferably ranging from 4-14 cm, with the width
usually ranging from 0.5 cm to 2.5 cm. The surgeon uses plain film
X-ray of the humerus to be treated. The required length is defined
by measuring the distance from the inner humeral head at the site
of insertion to about 3 cm below the site of fracture. The diameter
is at least 0.5 cm smaller than the inner diameter of the cortex of
the humeral shaft (at its narrowest point along the balloon's
length).
Proximal Tibial Plateau Fracture Balloon
The tibial fracture is shown in FIG. 19A in which a balloon 180 is
placed in one side 182 of a tibia 183. The balloon, when inflated,
compacts the cancellous bone in the layer 184 surrounding the
balloon 180. A cross section of the balloon is shown in FIG. 19C
wherein the balloon has a pair of opposed sides 185 and 187 which
are interconnected by restraints 188 which can be in the form of
strings or flexible members of any suitable construction. The main
purpose of the restraints is to make the sides 185 and 187
substantially parallel with each other and non-spherical. A tube
190 is coupled to the balloon 180 to direct liquid into and out of
the balloon. The ends of the restraints are shown in FIGS. 19B and
19D and denoted by the numeral 191. The balloon is inserted into
and taken out of the tibia in the same manner as that described
above with respect to the vertebral bone. FIG. 19B shows a
substantially circular configuration for the balloon; whereas, FIG.
19D shows a substantially elliptical version of the balloon.
The dimensions of the proximal tibial plateau fracture balloon vary
as follows:
The thickness or height of the balloon will vary from 0.5 cm to 5.0
cm.
The anterior/posterior (front to back) dimension will vary from 1.0
cm to 6.0 cm.
The side to side (medial to lateral) dimension will vary from 1.0
cm to 6.0 cm.
The selection of the appropriate balloon to treat a given tibial
plateau fracture will depend on the radiological size of the
proximal tibial and the location of the fracture.
Femoral Head Balloon
In the case of the femoral head, a balloon 200 is shown as having
been inserted inside the cortical bone 202 of the femoral head
which is thin at the outer end 204 of the femur and which can
increase in thickness at the lower end 206 of the femur. The
cortical bone surrounds the cancellous bone 207 and this bone is
compacted by the inflation of balloon 200. The tube for directing
liquid for inflation purposes into the balloon is denoted by the
numeral 209. It extends along the femoral neck and is directed into
the femoral head which is generally spherical in configuration.
FIG. 20A shows that the balloon, denoted by the numeral 200a, can
be hemispherical as well as spherical, as shown in FIG. 20. The
balloon 200 is inserted into and taken out of the femoral head in
the same manner as that described with respect to the vertebral
bone. The hemispherical shape is maintained in this example by
bonding overlapping portions of the bottom, creating pleats 200b as
shown in FIG. 20A.
The dimensions of the femoral head balloon vary as follows:
The diameter of the femoral head balloon will vary from 1.0 cm to
up to 4.5 cm. The appropriate size of the femoral head balloon to
be chosen depends on the radiological or CT scan size of the head
of the femur and the location and size of the avascular necrotic
bone. The dimensions of the hemispherical balloon are the same as
the those of the spherical balloon, except that approximately one
half is provided.
Prevention of Hip Fracture
FIG. 21 illustrates a "boomerang" balloon 210 adapted for
preventing hip fracture. When inflated, the "boomerang" balloon 210
is a cylinder which gradually bends in the middle, like a
boomerang, and extends from about 0.5 cm from the end of the
femoral head 211 through the femoral neck 212 and down into the
proximal femoral diaphysis 213 about 5-7 cm past the lesser
trochanter 214. Balloon 210 preferably maintains its shape by rings
of inelastic material (215 is one of them) held closer together on
one side by attachment to a shorter inelastic band 216 running the
length of the side of balloon and further apart by attachment to a
longer inelastic band 217 bonded on the opposite side.
After and prior to inflation, balloon 210 is folded back (shown in
dotted lines at 218) against the inflation tube 219. Prior to
inflation, the balloon 210 is also rolled up and held against the
inflation tube with loose attachments that break when the balloon
is inflated. To insert the balloon on its inflation tube into the
hip, the surgeon uses a power drill under radiographic guidance to
create a cavity 220 that is usually 4-6 mm wide starting at the
lateral femoral cortex 221 and proceeding into the femoral head
211. Inflation of balloon 210 into the greater trochanteric region
222 instead of down the femoral diaphysis 213 is not desirable and
is prevented by the shape of the balloon, by its placement and
correct orientation (the deflated balloon facing the lesser
trochanter). After the balloon 210 has been inflated within the
cavity 220 (see the dotted lines in FIG. 21), the predetermined
size and shape of the balloon biases the proximal portion of the
balloon downward into the lesser trochanter. Optionally, a second
cavity can be drilled down into the diaphysis, starting from the
same entry point or from the other side.
Patients with bone density in the hip below a threshold value are
at increased risk of hip fracture, and lower densities create
greater risk. Patient selection is done through a bone density
scan. The balloon length is chosen by the surgeon to extend about
0.5 cm from the end of the femoral head, through the femoral neck
and into the proximal femoral diaphysis, usually about 4-8 cm below
the lesser trochanter. The balloon diameter is chosen by measuring
the inner cortical diameter of the femoral neck (the most narrow
area) and subtracting 0.5 cm. The preferred dimensions of the
"boomerang balloon" are a total length of 10-20 cm and a diameter
of about 1.0-2.5 cm. (A "humpback banana" balloon with appropriate
length may also be useful in hip fracture prevention, as long as
the "humpback" width does not exceed the allowed femoral neck
dimensions.)
Patients having the lowest bone densities in the femoral head may
require greater compacting in the femoral head, which may, for
example, be provided by using two balloons, one after the other:
the "boomerang" followed by the femoral head balloon (inserted at
the same point and expanded prior to inserting any supporting
material.) Alternatively, the "boomerang" balloon may be adapted to
have a distal portion that approximates the shape of the femoral
head balloon.
Other Uses, Methods And Balloons
The cavity created by the balloon can be filled with a
medically-appropriate formulation of a drug or a growth factor. As
an example of delivering a drug, a typical dose of the antibiotic,
gentamicin, to treat a local osteomyelitis (bone infection), is 1
gram (although the therapeutic range for gentamicin is far greater,
from 1 nanogram to 100 grams, depending on the condition being
treated and the size of the area to be covered). A
medically-suitable gel formulated with appropriate gel materials,
such as polyethylene glycol, can contain 1 gram of gentamicin in a
set volume of gel, such as 10 cc. A balloon with this volume whose
shape and size is appropriate for the site being treated (that is,
the balloon cannot move and thereby break the cortical bone when
inflated at the chosen site) can be used to compact the infected
cancellous bone. This creates a space which can be filled with the
antibiotic gel in an open or minimally invasive procedure. This
places and holds the required amount of drug right at the site
needing treatment, and protects the drug from being washed away by
blood or other fluids. Not only can the dose be optimized, but
additional doses can be applied at later times without open
surgery, enhancing the therapeutic outcome. If the required cavity
for the optimal drug dose weakens the bone, the bone can be
protected from future fracture with a cast or with current internal
or external metal or plastic fixation devices. The therapeutic
substance put into bone may be acting outside the bone as well. A
formulation containing chemotherapeutic agent could be used to
treat local solid tumors, localized multiple myeloma or even a
nearby osteosarcoma or other tumor near that bone.
As an alternative, to deliver therapeutic substances, balloons can
be dipped in a medical formulation (often a dry powder, liquid or
gel) containing a medically-effective amount of any desired
antibiotic, bone growth factor or other therapeutic agent to coat
the balloon with the above-mentioned substance before it is
inserted into a bone being treated. Optionally, the balloon can be
wholly or partially inflated with air or liquid before the coating
is performed. Optionally, the coated balloon can be dried with air
or by other means when the applied formulation is wet, such as a
liquid or a gel. The balloon is refolded as required and either
used immediately or stored, if appropriate and desired. Coated on
the balloon, therapeutic substances can be delivered while
cancellous bone is being compressed, or with an additional balloon
once the cavity is made.
The methods described above can also be used to coat Gelfoam or
other agents onto the balloon before use. Inflating the
Gelfoam-coated balloon inside bone will further fill any cracks in
fractured bone not already filled by the compressed cancellous
bone.
FIGS. 22A-C schematically illustrate one system and method for
delivering a therapeutic substance to the bone according to the
present invention. As shown in FIG. 22A, an inflated balloon 229
attached to an inflating tube 230 is stabilized with a clip 231
that couples tube 230 to a wire 232. As shown in FIG. 22B, a
measured amount of gel formulation containing the desired amount of
substance 233 is uniformly dispensed from a container 234,
preferably in thin lines 235, onto the outer surface of a balloon
236. As shown in FIG. 22C, the coated balloon 237 is then deflated
and allowed to dry until the get sets. The coated balloon 237 is
then ready for packaging for use by the surgeon. Of course, the
balloon can also be coated without prior inflation. In addition,
the coating substance can be the desired compound alone in its
natural state (solid, liquid or gas) or in an appropriate
formulation, including a dry powder, an aerosol or a solution. The
optional drying time will, of course, depend on the nature of the
compound and its formulation.
Delivering a therapeutic substance on the outside of the balloon
used to compact the bone or with a second (slightly larger) balloon
after the bone is compacted, is qualitatively different than
putting formulated drug into the cavity. When delivered while
compressing the bone, the substance becomes incorporated into the
compacted bone. This can serve as a way to instantly formulate a
slow release version of the substance. It simultaneously allows the
surgeon to fill the cavity with an appropriate supporting material,
like acrylic bone cement or biocompatible bone substitute, so no
casting or metal fixation is required. Such a combination allows
the surgeon, for example, to percutaneously fix an osteoporotic
fracture while delivering a desired therapeutic substance (like an
antibiotic, bone growth factor or osteoporosis drug) to the site.
Thus, casts or metal fixation devices are generally not ever
required.
Medically-effective amounts of therapeutic substances are defined
by their manufacturers or sponsors and are generally in the range
of 10 nanograms to 50 milligrams per site, although more or less
may be required in a specific case. Typical antibiotics include
gentamicin and tobramycin. Typical bone growth factors are members
of the Bone Morphogenetic Factor, Osteogenic Protein, Fibroblast
Growth Factor, Insulin-Like Growth Factor and Transforming Growth
Factor alpha and beta families. Chemotherapeutic and related agents
include compounds such as cisplatin, doxorubicin, daunorubicin,
methotrexate, taxol and tamoxifen. Osteoporosis drugs include
estrogen, calcitonin, diphosphonates, and parathyroid hormone
antagonists.
The balloons described in this invention can be used in open
surgical procedures at the sites discussed above to provide an
improved space for inserting orthopedic implants, bone graft, bone
substitutes, bone fillers or therapeutic substances. The size and
shape of balloon chosen would be determined by the site being
treated and then by the size, shape or amount of material that the
surgeon wants to insert into the remaining bone. Square and
rectangular balloons can be used at any site for the placement of
bone substitutes like hydroxyapatites which are available in those
shapes. Balloons would be made to match those predetermined sizes,
and the surgeon would chose the balloon to fit the size of material
chosen.
To insert materials which do not flow into the balloon-made cavity,
like hydroxyapatite granules or bone mineral matrix, the surgeon
can push them down a tube with a long pin whose diameter is
slightly more narrow than the inner diameter of the canula through
procedures which the minimally-invasive procedure is taking place.
During open surgery, the surgeon can approach the bone to be
treated as if the procedure is percutaneous, except that there is
no skin and other tissues between the surgeon and the bone being
treated. This keeps the cortical bone as intact as possible. If the
material to be inserted does not flow and should not be pushed into
the cavity through a canula (as in the case of the hydroxyapatite
block, because that can cause damage), the surgeon can make the
cavity using the "minimally invasive" approach, then punch a hole
using standard tools (such as a punch, gouge or rasp) into one side
of the cortical bone to allow insertion of the block. This same
approach can be used for implanting a metal prosthesis, such as the
metal tibial component of a total knee replacement system.
Different sizes and/or shapes of balloons may be used at sites not
specified above, such as the jaw bones, the midshaft of the arm and
leg bones, the cervical vertebral bodies, the foot and ankle bones,
the ribs and the like. One of the keys to choosing balloon shape
and size in treating or preventing bone fracture is the teaching of
this application that, optimally, about 70-90% of the cancellous
bone needs to be compacted in cases where the bone disease causing
fracture (or the risk of fracture) is the loss of cancellous bone
mass (as in osteoporosis). Compacting less than the optimal 70-90%
of the cancellous bone at the site being treated (or 40-99% as the
workable range) may leave too much of the diseased cancellous bone
at the treated site. The diseased cancellous bone remains weak and
can later collapse, causing fracture despite treatment. With this
principle, the allowed shapes and minimum sizes for any chosen bone
are explained and defined.
There are specific exceptions to the 70-90% rule, as described in
this specification. One is when the bone disease being treated is
localized, as in avascular necrosis, where local loss of blood
supply is killing bone in a limited area. In that case, the
balloons can be smaller, because the diseased area requiring
treatment is smaller. A second exception is in the use of the
devices to improve insertion of solid materials in defined shapes,
like hydroxyapatite and components in total joint replacement. In
these cases, the balloon shape and size is defined by the shape and
size of the material being inserted. Another exception is the
delivery of therapeutic substances. In this case, the cancellous
bone may or may not be affected. If it is not, it is being
sacrificed by compacting it to improve the delivery of a drug or
growth factor which has an important therapeutic purpose. In this
case, the bone with the drug inside is supported while the drug
works and then the bone heals through casting or current fixation
devices.
Another key to choosing balloon shape and size is the teaching of
this invention that inelastic balloon restraints are generally
required and that inelastic balloon materials are preferred. These
materials safely and easily prevent the balloon from expanding
beyond its predetermined shape and size which is defined by the
limits of the normal dimensions of the outside edge of the
cancellous bone (which is the inside of the cortical bone). A
balloon which is too big, for example, creates the risk of
immediate fracture, so this defines the upper limits of balloon
sizes at each site. With many typical angioplasty balloons,
surgeons usually rely on monitoring pressure (instead of the
balloon design features of this invention) to prevent their
balloons from inflating too much. This requires greater surgical
skill than the teachings of this application, which are to take an
X-ray of the site to be treated and measure the important
dimensions as described herein. In addition, in bone treatment,
relying on pressure can result in an inferior clinical outcome. The
surgeon generally will not know in advance what pressure is
required to completely compact the cancellous bone, because this
varies depending on the thickness of the cancellous bone and the
extent to which it has lost density due to its disease. The surgeon
is likely to underinflate the balloon to avoid the harsh
consequences of overinflation and immediate fracture. This leaves
too much cancellous bone and can lead to future fracture.
Another teaching of this application is that it requires maximal
pressures equally exerted in all directions to compress cancellous
bone. This is an inherent property of the balloons drawn in figures
in this application and all the others described in the
specification. If the balloon design does not allow this, it
usually will not compress cancellous bone. The shape of the
cancellous bone to be compressed, and the local structures that
could be harmed if bone were moved inappropriately, are generally
understood by medical professionals using textbooks of human
skeletal anatomy along with their knowledge of the site and its
disease or injury. Ranges of shapes and dimensions are defined by
the site to be treated. Precise dimensions for a given patient are
determined by X-ray of the site to be treated, the therapeutic goal
and safety constraints at the site. For diseased bone, replacement
of the most of the cancellous bone is usually desired, so a balloon
whose shape and size will compress around 70-90% of the volume of
the cancellous bone in the treated region will be chosen. However,
balloons that are smaller or larger may be appropriate,
particularly where delivery of a therapeutic substance is the main
goal. There, the balloon size could be chosen by the desired amount
of therapeutic substance, keeping in mind that the balloon should
not displace the cortical bone beyond its normal dimensions.
* * * * *